Generally, various types of separators are used to separate liquids and solids. For example, oilfield drilling operations use separators with screens to remove solids from a slurry. One type of apparatus used to remove solids from drilling mud is commonly referred to in the industry as a “shale shaker.” A shale shaker, also known as a vibratory separator, is a vibrating sieve-like device upon which returning used drilling mud is deposited and through which substantially cleaner drilling mud emerges.
Oilfield drilling fluid, often called “mud,” serves multiple purposes in the industry. Drilling mud acts as a lubricant to cool rotary drill bits and facilitate faster cutting rates. Furthermore, the drilling mud counterbalances pressure encountered in subterranean formations. Various weighting and lubrication agents are mixed into the drilling mud to obtain the correct mixture for the type and construction of the formation to be drilled. Because the mud evaluation and/or mixture process may be time consuming and expensive, drillers and service companies prefer to reclaim and reuse the returned drilling mud. Another significant purpose of the drilling mud is to carry the cuttings away from the drill bit to the surface. In the wellbore, the cutting solids enter the drilling mud and must be removed before the drilling mud may be reused.
Typically, shale shakers use filtration screens to separate drill cuttings from drilling fluid in on-shore and off-shore oilfield drilling. The separating screens have a mesh stretched across a frame. The mesh allows particles and/or fluid below a predetermined size to pass through the separating screen. One or more vibration motors are connected to the frame of the separating screen. The separating screen is vibrated while the mixture of particles and/or fluids is deposited on an input side. The vibration improves separation and conveys the remaining particles to a discharge end of the separating screen.
The particles that do not pass through the mesh may be introduced to additional processing equipment, such as dryers, hydrocyclones, centrifuges and/or thermal desorption systems. Additionally, particles that do not pass through the mesh are collected in a bin and/or a pit. The particles and/or fluid that pass through the mesh are collected in a pan and/or a sump below the separating screen.
The slurry is poured onto a back end of the vibrating screen, flowing toward the discharge end of the basket. Large particles that are unable to move through the screen remain on top of the screen and move toward the discharge end of the basket where they are collected. The fluids flow through the screen and collect in a reservoir beneath the screen.
A continuing desire exists for shakers having increased fluid capacity, increased fluid flow-through rates across the screens, and/or improved fluid removal efficiencies.